The long-term goal of the research proposed is develop and test a clinical paradigm to identify prospectively right hemisphere (RH) seizure resection patients at risk for post-surgical speech perception deficits. Based on preliminary studies, we hypothesize that RH auditory areas, normally recruited to compensate for degradation of the speech signal under adverse listening conditions, are disrupted by surgery and/or chronic seizure effects. To test this hypothesis, we will implement three methodological approaches to assess the functional and structural integrity of the auditory system before surgery. We will then test the feasibility and potential clinical utility of combining these methods into a single clinical paradigm. First, we will implement repeated-measures behavioral testing using standardized and experimental tasks. Statistical modeling will help to identify resection parameters (size, location) associated with post-surgical behavioral auditory deficits. Second, electrophysiology studies will be performed to provide objective measures of auditory function and to investigate inter-hemispheric differences. Third, patients will undergo pre-surgical neuroimaging studies to identify functional abnormalities of cortical organization (fMRI), and structural abnormalities of auditory cortex (volumetric MRI) and the underlying white matter pathways (diffusion tensor MRI). Electrophysiology and neuroimaging results will be correlated with patients' behavioral performances. This research project constitutes the initial phase of a long-term research effort to investigate the neural bases of auditory dysfunction in chronic seizure patients. The feasibility studies proposed are well suited to the goals of the R21 program; We will integrate behavioral, electrophysiological, neuroimaging, and statistical methods to develop a new clinical paradigm. Completion of this initial research project will provide the basis for future investigations.